The aim of this research is to describe the relationship between the structure and function of antibody receptors and of those molecules that interact with these receptors in an immune response. Our appproach is to analyze the structures of a variety of cell-surface molecules of thymus-derived lymphocytes (T-cells) and to define their function and interactions in terms of the molecular mechanisms of cell recognition phenomena in the immune response. Microchemical methods for structural analysis are being developed and used in conjunction with functional cellular assays. The specific goals are: 1) to develop assays and chemical methods for structural characterization of the T-cell receptor; 2) to analyze the structure of the urinary protein alpha1-microglobulin, counterparts of which are found on T-cells; 3) to determine the structure of TL antigens and compare it with that of H-2 and other lymphocyte antigens; 4) to develop an extensive program of microchemical methods for the complete structural analysis of cell surface proteins; 5) to compare fetal and tumor-specific antigens with other cell-surface molecules such as H-2 antigens and with immunoglobulins in order to determine whether their variability is based on similar principles. The overall goal of these studies is to clarify our understanding of the ontogeny, physiology and genetic mechanism of the immune response.